BUG24938411: Fix datetime microsecond conversion

This patch fixes the microsecond conversion from MySQL datetime to
Python datetime when using fractional values with the C extension
enabled.

A test was added for regression.

Author: nmariz

CHANGES.txt

@@ -17,6 +17,7 @@ v8.0.23
 - BUG#31882419: Fix error when getting the connection ID from a CMySQLConnection
 - BUG#29195610: Fix cursor.callproc() using namedtuple and dictionary cursors
 - BUG#26834307: Make cursor.fetchone() and cursor.fetchmany() PEP 249 compliant
+- BUG#24938411: Fix datetime microsecond conversion
 
 v8.0.22
 =======

src/mysql_capi_conversion.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2020, Oracle and/or its affiliates.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2.0, as
@@ -453,7 +453,7 @@ mytopy_datetime(const char *data, const unsigned long length)
     if (data != end && end - data >= 2 && *data == '.')
     {
         // Fractional part
-        int field_length= 6;   // max fractional - 1
+        int field_length= 5;
         data++;
         value= (unsigned int)(*data - '0');
         while (data++ != end && isdigit(*data))
@@ -463,6 +463,13 @@ mytopy_datetime(const char *data, const unsigned long length)
                 value= (value * 10) + (unsigned int)(*data - '0');
             }
         }
+        if (field_length >= 0)
+        {
+            while (field_length-- > 0)
+            {
+                value*= 10;
+            }
+        }
         parts[6]= value;
     }
 

tests/test_bugs.py

@@ -5781,3 +5781,30 @@ def test_callproc_cursor_types(self):
         with self.cnx.cursor(prepared=True) as cur:
             self.assertRaises(errors.NotSupportedError,
                               cur.callproc, 'sp_bug29195610', (2020,))
+
+
+class BugOra24938411(tests.MySQLConnectorTests):
+    """BUG#24938411: FIX MICROSECOND CONVERSION FROM MYSQL DATETIME TO PYTHON
+    DATETIME.
+    """
+
+    @tests.foreach_cnx()
+    def test_datetime_fractional(self):
+        with self.cnx.cursor() as cur:
+            cur.execute("DROP TABLE IF EXISTS bug24938411")
+            cur.execute(
+                "CREATE TABLE bug24938411 "
+                "(mydate datetime(3) DEFAULT NULL) ENGINE=InnoDB"
+            )
+            cur.execute(
+                'INSERT INTO bug24938411 (mydate) '
+                'VALUES ("2020-01-01 01:01:01.543")'
+            )
+            cur.execute(
+                "SELECT mydate, CAST(mydate AS CHAR) AS mydate_char "
+                "FROM bug24938411"
+            )
+            row = cur.fetchone()
+            self.assertEqual(row[0], datetime(2020, 1, 1, 1, 1, 1, 543000))
+            self.assertEqual(row[1], "2020-01-01 01:01:01.543")
+            cur.execute("DROP TABLE IF EXISTS bug24938411")